Papers by Author: Yu Xia Pang

Abstract: Calcium lignosulfonate (CL) was separated into three fractions with different molecular weight by using ultrafiltration membranes, and the effect of the composition of commercial CL on the setting time of Portland cement with anhydrite was studied in this paper. Results show that the CL fraction with the cut-off molecular weight of less than 150 (CL-A) shortens setting time most. Further analysis indicates that the content of reducing sugar in CL-A reaches to 15.3%, including mannose, glucose, galactose, xylose and arabinose, and these five kinds of monosaccharides are found to be the main components of inducing quick set of cement. Ultrafiltration is an effective method to remove most of the reducing sugar in CL and weaken the quick set of Portland cement with anhydrite.

Abstract: The dispersive effect of four lignosulfonates (Kinsperse126, sodium lignosulfonate, magnesium lignosulfonate and a modified lignosulfonate GCL4-1) on the stability of Dimethomorph (DMM) water based suspension with different particle sizes was investigated. DMM suspension without dispersant was unstable owing to the strong aggregation of particles, while the stability was increased after the addition of lignosulfonate (LS), which can be adsorbed on the particle surface and weaken the aggregation of particles. Moreover, the higher sulfonated degree of LS, the better the dispersible ability was. Compared with LS of high sulfonated degree which could improve the zeta potential of DMM, LS with high molecular weight had larger adsorption capacity and steric effect on the pesticide particles. Associated with the dispersive behavior of DMM suspension, the electrostatic repulsion was found to be the more important factor impacting the stability of DMM suspension by comparison with the steric effect.

Abstract: Lignosulfonate (LS) is an important dispersant for wettable powder (WP). Though domestic products of lignosulfonate in China are very cheap compared to imported products, their performance is often inferior. Two modified products GCL4-1 and GCL4-A, from sodium lignosulfonate and alkali lignin respectively, were developed and their dispersive effects on the performance of 40% myclobutanil wettable powder (WP) were studied compared with the imported product Borresperse Na and the domestic product SXMN. Results show that GCL4-1 and GCL4-A have superior performance in these properties: suspensibility, wettability, surface tension, contact angle and solution retention. GCL4-A was found to be a suitable dispersant for the wettable powder pesticide for it has the best performance per unit price.